Pump systems and methods of this kind for controlling and operating pump systems are well known from the state of the art and are regularly used for surface coating, i.e. to apply or spray multi-component material onto a surface. The multi-component material consists of one or more basic component materials and a hardener component material, each of these component materials being stored separately in liquid tanks. Each liquid tank is associated with a pump for pumping the respective component material. Preferably, pneumatically driven piston pumps are used in this context; however, other types of pumps may be used as well. By means of the respective pumps, the component materials are pumped to a so-called mixer and are mixed within the mixer in such a manner that the thus formed multi-component material can harden. From the mixer, the multi-component material is pumped under pressure to a so-called spray gun by means of the pump. The spray gun does not necessarily have to be in the shape of a gun, but can be any type of nozzle by means of which the multi-component material can be sprayed onto a surface by atomization. Optionally, one or more heaters can be provided for adjusting the temperature of the component material. Together, the pumps and the liquid tanks form a pump device, which can be operated and controlled by an operator via an operating means.
In many cases, a pump device of this kind is designed portable, allowing it to be easily placed in the proximity of the items to be coated. Via the operating means, the pump device can be switched on and off, and it is also possible for a mixing ratio of the component materials to be adjusted at the operating means. An adjustment of this kind usually takes place by varying the respective delivery rate of the pumps. Hence, the operating means can also have various sensors, flow-rate measuring devices, stroke-length measuring devices or similar means for determining and influencing a delivery rate of the pumps. Moreover, a delivery line of the pumps as well as of the mixer and of the spray gun must always be purged after use or when changing colors, for example. Hence, the operating means often has a so-called purging function.
A pump unit formed by a pump device, a mixer and a spray gun is used in situ for coating surfaces with an anticorrosive coating or paints on or in ships, metal buildings or industrial installations, for example. The substantial aspect is that the pump unit can be easily transported by an operator and be put into operation at the respective work site. A delivery line from the pump device to the spray gun can have a length of a few meters to several hundred meters. This is especially the case when surface coating takes place in difficult-to-access places, such as within a ship's hull.
It is further known for stationarily installed pump units to be used instead of transportable pump units. Pump units of this kind are provided with a pump device having more than two pumps and liquid tanks. Said pump units can be used in a paint booth, for example, where it will thus be possible to have a plurality of component materials, such as different colors, in simultaneous use. For instance, multiple component materials or colors can thus be simultaneously mixed with a hardener component material and be sprayed with the spray gun. The spray gun does not necessarily have to be handled by an operator; it can also be mounted on a robot arm. In this case, it is also possible to continuously change a color, for example, by allowing for automatic intermediate purging of the relevant delivery lines as well as of the mixer and the spray gun. The substantial aspect is that the pump device is configured according to individual requirements to have a number of up to 30 pumps and liquid tanks, for example, a shared operating means for controlling and operating all pumps being provided. In case of this configuration of a pump unit, however, it is disadvantageous if a function of the operating means or even just one pump fails, for example. This will lead to a standstill of the entire pump unit for a longer period of time because in addition to an error search, the pump unit will have to shut down in order to replace a pump or components of the pump device. The pump units are also designed for an individual application in each case, such as for a specific paint booth. In case of potential changes to the paint booth or in case of subsequent use of the pump unit for a different purpose, extensive restructuring of the pump unit is required.